SAP PI to Mainframe (ftp.site command issue)

We are trying to deliver a file using SAP PI 7.5/ FTP adapter to Mainframe system using dataset name for file dispostion M (modify) we are using file construction mode as appened and for ile dispostion N (new) we are using file construction mode as create

As per SAP note "1530149" we are using "ftp.site" command and use parameters like format, length, block size (RECFM=F LRECL=100 BLKSIZE=1000) in advance mode however the audit logs show the record length (LRECL) and block size (BLKSIZE) is not using the parameter value and in fact it is using default value 200